Over the past few days millions of Italians have been watching dramatic scenes of ethnic cleansing on their television screens.

But the images are not of the Holocaust, Rwanda or Darfur: it is the first film to be made in Italy about the massacre of up to 15,000 men, women and children, many killed by Yugoslav communists towards the end of the second world war just for being Italian.

It is the hardest-hitting part of a government campaign to draw attention to a little-known event which was marked for the first time yesterday, 60 years on, with a national day of remembrance.

Parliament observed a minute's silence and the foreign minister, Gianfranco Fini, and other dignitaries attended a military ceremony in the north-eastern city of Trieste, where many of the crimes were committed.

Red, white and green lapel ribbons and 3.5m special stamps were issued by the newly formed 10th February Committee.

Between 1943 and 1945 thousands of Italians living in Trieste, Gorizia and the Istrian peninsula were tortured, shot or pushed to their deaths in rocky chasms by communists determined to cleanse Yugoslavia of its Italian population.

Some were sympathisers of Benito Mussolini's fascist regime in Italy. Others were innocent civilians.

They were left, some still alive to rot in natural ditches known in Italian as foibe.

About 300,000 Italians had been forced to flee the area by 1947 and estimates of the number killed vary between 6,000 and 15,000.

After the war the massacres were swept under the political carpet as Italy sought to heal its wartime wounds.

Most of the so-called foibe killings have never been properly investigated.

Italian history books have traditionally portrayed communist partisans as national heroes who fought to free the country from fascism.

Italian communists and today's hard left have long tried to bury the matter, out of embarrassment.

But the centre-right government of Silvio Berlusconi, who personally considers communists a lingering threat to Italy, is determined to make sure that as many Italians as possible are aware of this dark part of the country's past.

In the run up to the memorial day, more than 10 million people watched the first film on the subject, Il Cuore nel Pozzo (Heart in the ditch) which cost the state television service RAI €4.5m (£3.09m) to produce.

The film shows the atrocities through through the eyes of a group of children who manage to escape, though the priest accompanying them is shot.

"If we look back to the 20th century we see pages of history we'd prefer to forget," Mr Berlusconi said in advance of yesterday's events.

"But we cannot and should not forget."

The communications minister, Maurizio Gasparri, a member of the National Alliance, which traces its roots back to Mussolini's fascist party, said: "We must pull from this abyss of lies a truth hidden by the imposition of a cultural bias."

The party has openly supported Il Cuore nel Pozzo, which had its premiere in a conference hall built for Mussolini outside Rome, calling it "a historic event".

While the Italian hard-left has long tried to bury this part of the country's history, centre-left politicians have agreed that it is time to face up to the past

Last week the mayor of Rime, Walter Veltroni, went to the killing grounds to pay homage to the dead.

"The Holocaust was a tragedy without equal, but it was not the only tragedy of the 20th century," he said.

"What is certain is what I have seen here is witness to a guilty silence, even involving the left, the communists".

But critics argue that the film fails to address all sides of the story. The region around Trieste and the Istrian peninsula had come under Italian control after the first world war and had been brutally "Italianised" by Mussolini's henchmen.

The Slovenian foreign minister, Ivo Vajgl, criticised the making of the film last year as an "offence and provocation" to the Slovenian people.